Solid state lasers which are pumped by means of semiconductor laser sources have gained in significance in recent times. So-called laser diode arrays are used in order to provide adequately large pump power. The light emitting layer for the laser diode array comprises a plurality of strips. Arrays of this kind are assembled into so-called bars which typically have an edge length of approximately 10 mm and emit an average light power of up to 10 watts. Up to 50 watts of electrical power is required at a conversion efficiency of 20 to 30%. The heat developed must be conducted away since a temperature increase of the emitting layer presents two disadvantages. The life-time of the semiconductor is shortened and the wavelength of the emitted radiation is shifted so that it partly no longer lies in the range which is optimal for pump light absorption.
The bars are conventionally mounted on heat sinks which are usually made of copper. Each of these bars can be manufactured to have a different centroidal wavelength for its emitted radiation which must be matched to the wavelength of maximum absorption of the crystal to be pumped by the adjustment of the operating temperature.
German Patent 3,706,635 discloses that the heat sink or the housing of a laser diode can be connected with a Peltier element and be equipped with a temperature sensor by means of which the adjustment of the required temperature is achieved. It is also known to provide the heat sinks with a temperature-regulating channel and to obtain the desired temperature by means of water cooling.
High pump source outputs for solid state lasers are obtained with arrangements wherein several bars are mounted one next to the other laterally of the solid state crystal. The bars must be mounted so as to be as close to each other as possible and each bar must be individually cooled so that the emitted radiation has the correct centroidal wavelength.